A fuel-cell power unit that can use natural gas, propane or diesel may in a couple of years provide on-site electricity to factories, computer-server farms and even your home. The solid oxide fuel cell , or SOFC, is also set to go mobile, with new systems providing auxiliary or "hotel" power to long-haul trucks. They may also keep a solar-powered surveillance drone in the sky for what could be years at a time. The latter's "two-way" fuel cell system could in addition electrolyze water to store backup energy as hydrogen to supplement intermittent solar and wind power. In time, say researchers, SOFCs might show up as range extenders--power units that augment batteries to extend distance driven electrically--in hybrid vehicles.